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How it Works

3. The receiver of a trapped miner converts the magnetic waves into electrical signals, which he hears as a voice, and he responds with his position.

When first responders arrive at a mine disaster or a building collapse, communicating with victims or other rescuers is usually impossible because radio waves can be blocked by metal, earth and stone. Even sites with low-frequency emergency radio systems suffer from slow data transfer that restricts use to simple text messages. But a novel system being developed by Ferro Solutions of Woburn, Mass., transmits voice signals with magnetic waves that travel through solid matter more easily than do radio signals.

Typical radios send signals on electromagnetic waves that oscillate at specific frequencies. Engineers at Ferro developed a portable communicator that translates these undulating waves into signals carried by magnetic fields with resonant frequencies that compatible radios can pick up through hundreds of yards of obstructions. The digital voice signal first passes through a transducer made of a composite that melds piezoelectric material (which generates a voltage when it deforms) with a magnetostrictive metal (which changes shape when it's exposed to a magnetic field). The transducer converts the radio signals into magnetic ones; another reverses this process when the signals reach the other radio.

Other Applications

Military: This year, Ferro Solutions will demonstrate a radio system U.S. troops can use to clear cave complexes or bunkers. During rescue operations at mass casualty events, such as the Haitian earthquake, military engineers equipped with these radios could stay in contact as they dig to save victims.